How much more fun would school have been had we known that, behind closed doors, teachers behaved like this? Greg Davies is as delinquent as the unruliest juvenile, the more so having been released from 13 unhappy years as a drama teacher. Now, he stars in E4's The Inbetweeners (as a teacher) and in the anarcho-puerile sketch troupe We Are Klang. He takes to the blackboard again for this solo Fringe debut, a biographical hour structured around the points in Davies's life – such as the one behind the show's title, Firing Cheeseballs at a Dog – when he finds himself living exclusively and gleefully in the moment.

The show I attend is unlikely to rank among them. Tonight, Davies must draw on all his pedagogic experience to silence unruly Saturday-night drunks in his crowd. He does so capably: he exudes authority as a performer while still playing the fool, which is a neat trick. A 6'8" master of silly ceremonies, he leads us from his Shropshire schooldays, and a chalkboard inventory of his schoolmates' nicknames, to his time as a teacher, obliged to educate "the strangest group of human beings ever assembled in one place". His thumbnail sketches of these pupils – the girl with the 1940s voice; the boy obsessed with tunnels – are among the set's highlights.

The show has a big heart, and Davies is a fine comic craftsman, burlesquing his own ridiculousness for our entertainment. But, while less crude than in his Klang guise, he still often relies on smut for laughs. And the unexceptional nature of some of his material – being fogeyish about young people's music; relating his dad's eccentric behaviour – is only just concealed by Davies's energetic, emphatic delivery. The teacher's lesson, though, is well worth learning: this is a celebration of mischief, a paean to senseless abandon.